This is really disappointing. XY ended, but Pikachu did not use Volt Tackle a single time in the whole series, not even once. Did Ash start using Electro Ball so often that he forget about such an important move of Pikachu?

Volt tackle is also a move that can't be learned by Pikachu in the games. A Pikachu has to be specially bred to have the move. This may have given some extra incentive to the shows' creators to sweep the move under the rug and forget about it. (pure speculation, of course)
– Shaymin GratitudeNov 3 '16 at 21:13

That is not at all true! Pokemon in the anime know more than 4 moves. The only reason why they don't in the game is because it's too much for the game's programming to handle plus there isn't a big enough screen for all the moves to fit. However; my personal opinion is i think that gamefreak is also trying to keep things simple.
– Ricky WoodsNov 17 '16 at 20:45

1

@RickyWoods, why do you say that? The only instance I've seen of a Pokemon knowing more than 4 was (I think) Lance's Dragonite who knew 10 to seem OP.
– VemonusNov 17 '16 at 20:57

I was watching Pokemon Sun and Moon season 1 episode 34 (subbed). In the middle of the episode, the subtitle said that Ash told Pikachu to use Volt Tackle.
Either this was a mistranslation or that he can use more than 4 moves now.

Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).